EINGBONE. 413 



Since a predisposition to develop sidebones may be inherited, ani- 

 mals sufl'eriilii from this disease should not be used for breeding 

 purposes unless the trouble is known to have originated fi'om an 

 accident. 



RINGBONE. 



A ringbone is the growth of a bony tumor on the ankle. This 

 tumor is, in fact, not the disease, but simply the result of an 

 inihunmatory action set up in the periosteum and bone tissue proper 

 of the pastern bones. (Plate XXXII, fig. 1.) (See also page 289.) 



Causes. — Injuries, such as blows, sprains, overwork in young, unde- 

 veloped animals, fast work on hard roads, jumping, etc., are among 

 the j^rincipal exciting causes of ringl)()ne. Horses most disposed to 

 this disease are those with short, upright pasterns, for the reason that 

 the shock of locomotion is but imperfectly dissipated in the fore legs 

 of these animals. Improper shoeing, such as the use of high calks, 

 a too great shortening of the toe and correspondingly high heels, 

 predispose to this disease by increasing the concussion to the feet. 



Symptoms. — The first symptom of an actively developed ringbone 

 is the appearance of a lameness more or less acute. If the bony 

 tumor forms on the side or upper parts of the large pastern, its 

 growth is generally unattended with acute inflammatory action, and 

 consequently produces no lameness or evident fever. These are called 

 '' false " rinebones. But when the tumors form on the whole circum- 

 fcrence of the ankle, or simply in front under the extensor tendon, or 

 behind under the flexor tendons, or if they involve the joints between 

 the two pastern bones, or between the small pastern and the coffin 

 bone, the lameness is always severe. These constitute the true ring- 

 bone. Besides lameness, the ankle of the aflfected limb presents more 

 or less heat, and in many instances a rather firm, though limited, 

 swelling of the deeper tissues over the seat of the inflanunatory proc- 

 ess. The lameness of ringbone is characteristic in that the heel is 

 first placed on the ground when the disease is in a fore leg, and the 

 ankle is kept as rigid as possible. In the hind leg, however, the toe 

 strikes the ground first, when the ringbone is high on the ankle, just 

 as in healtii. but the ankle is uuiintained in a rigid position. If the 

 bony growth is under the front tendon of the hind log. or if it 

 involves the coffin joint, the heel is brought to the ground first. In 

 the early stages of the disease it is not always easy to diagnose ring- 

 bone, but when the deposits have reached some size they can bo felt 

 and seen as well. 



The importance of a lingbono depends on its seat and often on its 

 size. If it interferes with the joints or with the tendons it may cause 

 an incurable lameness, even though snuill. If it is on the sides of the 

 large pastern, the lameness generally disappears as soon as the tunmr 

 has reached its growth and the inflannnation subsides. Even where 



